Image guided steering of a transducer array and/or an instrument

ABSTRACT

A method includes registering a region of interest in 3-D imaging data with an initial ultrasound image so that the region of interest is in an imaging plane of the initial ultrasound image. The method further includes acquiring a subsequent ultrasound image with a transducer array. The method further includes comparing the initial ultrasound image and the subsequent ultrasound image. The method further includes steering at least one of the transducer array or an instrument based on a result of the comparing so that at least one of the region of interest or the instrument is in the imaging plane.

TECHNICAL FIELD

The following generally relates to imaging and more particularly tosteering a transducer array and/or an instrument based on a region ofinterest in imaging data, and is described with particular applicationto ultrasound imaging data, but is also amenable to imaging datagenerated by other imaging modalities.

BACKGROUND

An ultrasound (US) imaging system includes a transducer array thattransmits an ultrasound beam into an examination field of view. As thebeam traverses structure (e.g., of a sub-region of an object or subject)in the field of view, sub-portions of the beam are attenuated,scattered, and/or reflected off the structure, with some of thereflections (echoes) traversing back towards the transducer array. Thetransducer array receives the echoes. In B-mode imaging, the echoes areprocessed (e.g., delayed, weighted and summed) to generate scanlines,which are subsequently converted based on a display monitor format anddisplayed as an image via the display monitor.

Ultrasound imaging has been used in a wide range of medical andnon-medical procedures. Examples of such procedures include surgery,biopsy, therapy, etc. In general, ultrasound images lack the quality ofother imaging modalities in the level of diagnostic information.Magnetic resonance imaging (MRI) images and/or computed tomography (CT)images have higher diagnostic quality, but MRI and CT images can bedifficult to acquire in real time during certain procedures. Incontrast, ultrasound images are relatively easily acquired in real timeduring procedures. Fusion of a pre-procedure MRI and/or CT image and anintra-operative US image data leverages the high image quality of theMRI and/or CT image data and the real-time imaging capability of US.

Transducer plane position has been determined by the operator'ssubjective interpretation of the reconstructed image on the ultrasounddisplay relative to known anatomical features. Unfortunately, this canlead to inaccurate positioning and/or repeat positioning. Patientmovement, surgical manipulations and deformations caused by measuringdevices modify the imaged organ such that regions of interest moverelative to the pre-procedure plan. Unfortunately, the transducer mayhave to be re-positioned every time the region of interest movesrelative to the imaging plane. With a prostate biopsy, a transrectalprobe often has to be manually rotated to sweep regions of interest andfollow needle movements. From the foregoing, positioning an imagingtransducer and/or instrument in certain procedures can be challengingand time consuming.

SUMMARY

Aspects of the application address the above matters, and others.

In one aspect, a method includes registering a region of interest in 3-Dimaging data with an initial ultrasound image so that the region ofinterest is in an imaging plane of the initial ultrasound image. Themethod further includes acquiring a subsequent ultrasound image with atransducer array. The method further includes comparing the initialultrasound image and the subsequent ultrasound image. The method furtherincludes steering at least one of the transducer array or an instrumentbased on a result of the comparing so that at least one of the region ofinterest or the instrument is in the imaging plane.

In another aspect, a system includes an ultrasound imaging apparatuswith a transducer array. The system further includes a memory withcomputer executable instructions, the computer executable instructionsincluding an auto-lock and guide mode, a registration algorithm, atracking algorithm, and a correction algorithm. The system furtherincludes a processor configured to execute the computer executableinstructions in response to activation of the auto-lock and guide mode,wherein the processor, in response to executing the computer executableinstructions, steers at least one of the transducer array or aninstrument based on the registration, tracking, and correctionalgorithms so that at least one of a region of interest or theinstrument is in an imaging plane of images generated by the ultrasoundimaging apparatus during a procedure.

In another aspect, a computer readable storage medium is encoded withcomputer executable instructions, which, when executed by a processor,causes the processor to: obtain a procedure plan, which 3-D imaging datawith a boundary of a region of interest marked therein, load theprocedure plan, obtain an ultrasound image, identify the region ofinterest in an imaging plane of the ultrasound image based on the regionof interest in the 3-D imaging data, acquire a subsequent ultrasoundimage, determine a difference in position of the region of interest inthe ultrasound image and the region of interest in the subsequentultrasound image, and control at least one of the transducer array or aninstrument based on the difference to maintain the region of interest orthe instrument is in the imaging plane.

Those skilled in the art will recognize still other aspects of thepresent application upon reading and understanding the attacheddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The application is illustrated by way of example and not limitation inthe figures of the accompanying drawings, in which like referencesindicate similar elements and in which:

FIG. 1 schematically illustrates an example system;

FIG. 2 schematically illustrates a variation of the example system ofFIG. 1 ;

FIG. 3 illustrates example workflow;

FIG. 4 illustrates an example;

FIG. 5 shows an example probe with a moveable transducer array at afirst position;

FIG. 6 shows an example of the probe of FIG. 5 with the moveabletransducer array at a second position;

FIG. 7 shows an example probe with a rotatable transducer array at afirst position;

FIG. 8 shows an example of the probe of FIG. 7 with the rotatabletransducer array at a second position;

FIG. 9 shows an example probe with an articulating transducer array at afirst position;

FIG. 10 shows an example of the probe of FIG. 9 with the articulatingtransducer array at a second position; and

FIG. 11 shows another example probe.

DETAILED DESCRIPTION

FIG. 1 illustrates a system 100. The system 100 includes an US imagingapparatus 102 with a probe 104 and a console 106. The probe 104 includesa 1-D (one-dimensional), 2-D (two-dimensional), or 3-D(three-dimensional) transducer array 108 with one or more transducerelements 110. The transducer array 108 can be linear, curved, and/orotherwise shaped, fully populated, sparse and/or a combination thereof,etc. The transducer elements 110 are configured to transmit ultrasoundsignals and receive echo signals. As described in greater detail below,in one instance, the transducer array 108 is at least one ofelectronically and/or mechanically steerable, automatically and/ormanually.

The system 100 further includes a probe guide 111. The probe guide 111is configured to support the probe 104 at least during a procedure. Inone instance, the probe guide 111 holds the transducer array 108 at astatic position, and the transducer array 108 is electronically and/ormechanically steered. In another instance, the probe guide 111 isalternatively and/or additionally moveable, and is used toelectronically and/or mechanically steer the transducer array 108,automatically (e.g., via a motor, etc.) and/or manually (e.g., by auser, a robot, etc.). In yet another embodiment, the probe guide 111 isomitted and the probe 104 is held by a user.

The console 106 includes transmit circuitry 112 configured to excite oneor more of the transducer elements 110, e.g., through a set of pulses(or a pulsed signal) that is conveyed to the transducer array 108, whichcauses the one or more of the transducer elements 110 to transmitultrasound signals. The console 106 further includes receive circuitry114 configured to receive echoes (RF signals) generated in response tothe transmitted ultrasound signals from the transducer array 108. Theechoes, generally, are a result of an interaction between the emittedultrasound signals and structure (e.g., flowing blood cells, organcells, etc.) in the scan field of view.

The console 106 further includes a beamformer 116 configured to processthe received echoes. In B-mode, this includes applying time delays andweights to the echoes and summing the delayed and weighted echoes. Thebeamformer 116 may be further configured for spatial compounding,filtering (e.g., FIR and/or IIR), and/or other echo processing. Theconsole 106 further includes a scan converter 118 configured to convertthe beamformed data for display via a display monitor 122. The console106 further includes an output device(s) 120, including the displaymonitor 122. The console 106 further includes an input device(s) 124,including a keyboard, a mouse, a trackball, a touchpad, a touchscreen,knobs, buttons, sliders, and/or other input device.

The console 106 further includes a controller 126 and non-transitorycomputer readable medium (“memory”) 128, which excludes transitorycomputer readable medium such as signals, carrier mediums, etc. Thecontroller 126 is configured to execute one or more instructionsembedded, encoded, stored, etc. in the memory 128. In this example, thememory 128 at least stores an auto-lock and guide mode 130, aregistration algorithm 132, a tracking algorithm 134, and a correctionalgorithm 136. The mode 130 can be activated and deactivated, e.g., viaa user actuating the input device(s) 124. In response thereto, thecontroller 126 executes the registration algorithm 132, the trackingalgorithm 134, and the correction algorithm 136.

The registration algorithm 132 includes instructions for registering aregion of interest (e.g., anatomical tissue of interest) identified inreceived 3-D reference planning image data with an imaging plane in areference real-time ultrasound image. A non-limiting example of asuitable registration is described in international application serialnumber PCT/US13/72154, filed on Nov. 27, 2013, and entitled“Multi-Imaging Modality Navigation System,” the entirety of which isincorporated herein by reference. PCT/US13/72154 describes an approachin which a location and a spatial orientation of a 2-D ultrasound sliceis located and/or mapped to a corresponding plane in a 3D volume. Otherapproaches are contemplated herein.

The tracking algorithm 134 tracks the region of interest in newlyacquired real-time ultrasound image to the region of interest in thereference previously acquired ultrasound image. Miss-alignment betweenthe regions of interest between frames may be due to movement of ascanned object, the region of interest, the probe 104, etc. Thecorrection algorithm 136 generates a position correction signal based ona location and/or position difference between the regions of interest.An example correction signal, e.g., may indicate the imaging plane needsto move to the left two millimeters (2 mm) to align the regions ofinterest.

The controller 126 is further configured to control various componentsof the system 100, such as the transmit circuitry 112 and/or the probeguide 111. In one instance, the controller 126, based on the positioncorrection signal, controls the transmit circuitry 112 and/or probeguide 111 to steer the imaging plane to align the regions of interest.The frequency of such control can be every frame, every other frame,every third frame, an irregular interval, on demand, based on apredetermined frequency, etc. Continuing with the above example, thecorrection signal may result in the probe 104 being moved to the lefttwo millimeters.

Alternatively and/or additionally, the controller 126, based on theposition correction signal, displays a message on the display monitor122. In one instance, the message includes alphanumeric characters inhuman readable format that indicates the user should move the probe 104(e.g., “please move the probe to the left 2 millimeters”). In anotherembodiment, the message could include graphics. For example, the messagecould include arrows pointing in a direction of movement, color or grayscale that indicates the movement, etc.

The system 100 further includes a 3-D imaging apparatus 138 with animaging portion 140, which includes one or more of ultrasound (US),magnetic resonance (MR), computed tomography (CT), single photonemission computed tomography (SPECT), positron emission tomography(PET), X-ray, and/or other imaging modality. The 3-D imaging apparatus138 generates the 3-D reference planning image data. The 3-D imagingapparatus 138 further includes a procedure planning portion 142, whichidentifies the region of interest in the 3-D reference planning imagedata using an automatic, semi-automatic, and/or manual approach. In oneinstance, this includes marking and/or otherwise identifying theboundary, the perimeter, and/or other landmark of the region ofinterest.

The illustrated system 100 further includes a data repository 144configured to store imaging data and/or other data. In this example, thedata repository 144 can store the 3-D reference planning image data, theregion of interest and/or a procedure plan. Examples of datarepositories include a picture archiving and communication system(PACS), a radiology information system (RIS), a hospital informationsystem (HIS), an electronic medical record (EMR), etc. The console 106can receive and/or retrieve the 3-D reference planning image data withthe region of interest from the data repository 144.

It is to be appreciated that the real-time active steering processdisclosed herein enables a workflow improvement through at least one ofaccuracy and speed improvements. In general, the mode 130 and algorithms132-138 can be regarded as an image-guided automated positioning system(iGAP). The iGAP allows the transducer array 108 to be dynamicallyguided, e.g., during a biopsy, surgical, treatment and/or otherapplication, based on a region of interest identified in a pre-procedureimage, such as an MRI, a CT, etc. image.

FIG. 2 schematically illustrates a variation of FIG. 1 in which theregistration algorithm 132, the tracking algorithm 134, and thecorrection algorithm 136 are located and executed remotely from theconsole 106, e.g., via computing resources 202 such as a “cloud” basedand/or other remote computing resource. The computing resources 202include a processor(s) 204 such as one or more microprocessor, centralprocessing units, and/or other processors. This example also includes acomputing apparatus 206, and the procedure planning portion 142 islocated in the computing apparatus 206 instead of the 3-D imagingapparatus 102.

FIG. 2 further includes an instrument guide 208. The instrument guide208 supports an instrument 210 such as a biopsy needle and/or otherdevice. The instrument guide 208, in one instance, is similar to theprobe guide 111 in that it can be used to steer the instrument 210,automatically (e.g., via a motor, etc.) and/or manually (e.g., by auser, a robot, etc.), to provide a guide to the region of interest,confirm the region of interest has been reached, record a biopsy, etc.Other variations include a combination of FIGS. 1 and 2 and/or otherconfiguration.

FIG. 3 illustrates example workflow in accordance with one or moreembodiments herein.

It is to be appreciated that the order of the following acts is providedfor explanatory purposes and is not limiting. As such, one or more ofthe following acts may occur in a different order. Furthermore, one ormore of the following acts may be omitted and/or one or more additionalacts may be added.

At 302, a region of interest (“ROI”) is identified in pre-procedure 3-Dimaging data and a plan is created.

At 304, the plan with the ROI is loaded on the ultrasound system 102,the computing resource 202, and/or other machine(s) running thealgorithms 132-136.

At 306, the system activates auto-lock and guide mode, e.g., in responseto receiving an input indicative of a user request to activateactive-contour lock.

At 308, the algorithms 132-136 are executed to steer the transducerarray 108 (and/or the instrument guide 208) so that the image plane in anewly acquired real time includes the region of interest (and/or theinstrument 210) for each real time image.

At 310, the real-time US image and the ROI are both displayed.

The above may be implemented by way of computer readable instructions,encoded or embedded on computer readable storage medium, which, whenexecuted by a computer processor(s), cause the processor(s) to carry outthe described acts. Additionally or alternatively, at least one of thecomputer readable instructions is carried by a signal, carrier wave orother transitory medium.

FIG. 4 illustrates an example of act 308 of FIG. 3 .

It is to be appreciated that the order of the following acts is providedfor explanatory purposes and is not limiting. As such, one or more ofthe following acts may occur in a different order. Furthermore, one ormore of the following acts may be omitted and/or one or more additionalacts may be added.

At 402, the transducer 108 is moved to an initial position.

At 404, the ROI location is determined relative to the imaging plane.

Subsequently, the ROI is displaced from the imaging plane, for example,due to subject movement, ROI movement, probe 104 movement, etc.

At 406, a current location of the ROI is measured in a newly acquiredreal time US image.

At 408, a position error is computed as a difference between thelocation of the ROI relative to the imaging plane and the measuredcurrent ROI location.

At 410, a position correct signal is computed based on the positionerror.

At 412, the position correct signal is used to update the location ofthe transducer array 108 (and/or the instrument guide 208) so that theimage plane in a newly acquired real time includes the region ofinterest (and/or the instrument 210) for each real time image.

Acts 406-412 are repeated for subsequently acquired real time US imageso the ROI is always imaged at a fixed location within the imagingplane. The process can be repeated in a control loop to servo the devicein real-time.

The above may be implemented by way of computer readable instructions,encoded or embedded on computer readable storage medium, which, whenexecuted by a computer processor(s), cause the processor(s) to carry outthe described acts. Additionally or alternatively, at least one of thecomputer readable instructions is carried by a signal, carrier wave orother transitory medium.

FIGS. 5-10 schematically show non-limiting examples of the probe 104 andthe transducer array 108.

FIGS. 5 and 6 show a configuration in which the probe 104 includes anelongate region or handle 502, including a proximal end 504 and a distalend 506, and a second region or probe tip 508, which is moveablyattached to the distal end 506. The transducer array 108 is disposed inthe second region 508. The second region 508 is configured to deflectabout a central axis 510. In this example, the second region 508deflects in the x, y and/or z directions. FIG. 5 shows a straight secondregion 508. FIG. 6 shows a deflected second region 508.

FIGS. 7 and 8 show a configuration in which the probe 104 includes anelongate region or handle 702, including a proximal end 704 and a distalend 706, and a second region or probe tip 708, which is rotatablyattached to the distal end 706. The transducer array 108 is disposed inthe second region 708. The second region 708 is configured to rotateabout a central axis 710. In this example, the second region 708 canrotate 360 degrees, more or less. FIG. 7 shows a straight non-rotatedsecond region 708. FIG. 8 shows a rotated second region 708.

FIGS. 9 and 10 show a configuration in which the probe 104 includes anelongate region or handle 902, including a proximal end 904 and a distalend 906. The proximal end 904 is affixed to an articulating member 908,and the transducer array 108 is disposed at the distal end 906. Thearticulating member 906 is configured to articulate about a central axis910. In this example, the articulating member 906 can articulate in thex, y and/or z directions. FIG. 9 shows the elongate region 902 extendingalong the central axis 910. FIG. 10 shows the elongate region 902articulated.

In general, the above configurations include a mechanical means forsteering the image plane. These means can be controlled electrically andautomatically, and/or manually by an operator. Furthermore, the imageplane can additionally be steered through selective excitation of thetransducer elements 110 of the transducer array 108. It is also to beappreciated that another embodiment includes a combination of two ormore of the embodiments depicted in FIGS. 5-10 . One or more otherembodiments are also contemplated herein.

For example, FIG. 11 shows a configuration in which the probe 104includes an elongate region or handle 1102, including a proximal end1104 and a distal end 1106, and a second region or probe tip 1108attached thereto, e.g., through a ball-and-socket joint. The transducerarray 108 (not visible) is disposed in the second region 1108. A conduit1110 between the transducer elements 110 and the console 106 extends outof the proximal end 1104. An image plane 1112 is shown in connectionwith the transducer array 108. In another example, rotating is achievedsynthetically by combining data generated by the transducer array 108.

The application has been described with reference to variousembodiments. Modifications and alterations will occur to others uponreading the application. It is intended that the invention be construedas including all such modifications and alterations, including insofaras they come within the scope of the appended claims and the equivalentsthereof.

What is claimed is:
 1. A method, comprising: identifying a region ofinterest in the 3-D image of a subject acquired prior to a procedure onthe subject, wherein the region of interest includes an anatomicaltissue of interest; acquiring, with a transducer array of an ultrasoundprobe of an ultrasound imaging apparatus, a first ultrasound image ofthe subject during the procedure; registering the 3-D image with thefirst ultrasound image by registering the region of interest in the 3-Dimage with the first ultrasound image to find the region of interest inan imaging plane of the first ultrasound image; acquiring, with thetransducer array of the ultrasound probe during the procedure and afteracquiring the first ultrasound image, a second ultrasound image of thesubject; identifying the region of interest in an imaging plane of thesecond ultrasound image; comparing a location of the region of interestin the imaging plane of the first ultrasound image and a location of theregion of interest in the imaging plane of the second ultrasound image;determining, based on a result of the comparing, a difference betweenthe location of the region of interest in the imaging plane of the firstultrasound image and the location of the region of interest in theimaging plane of the second ultrasound image; and steering, based on thedifference, an instrument guide so that an instrument carried by theinstrument guide is in an imaging plane of a third ultrasound image ofthe subject acquired with the transducer array of the ultrasound probeduring the procedure.
 2. The method of claim 1, wherein the differencerepresents a position error, and further comprising: computing aposition correction signal indicative of the position error; andsteering the instrument guide based on the position correction.
 3. Themethod of claim 1, further comprising: acquiring the 3-D image with animaging device.
 4. The method of claim 3, wherein the imaging deviceincludes at least one of a magnetic resonance imaging or a computedtomography scanner.
 5. The method of claim 1, further comprising:controlling the steering of the instrument guide with a processor of theultrasound imaging apparatus.
 6. The method of claim 1, furthercomprising: steering, based on the difference, the transducer array sothat a location of the region of interest in an imaging plane of a thirdultrasound image of the subject acquired with the transducer array ofthe ultrasound probe during the procedure, and after acquiring thesecond ultrasound image, spatially aligns with the location of theregion of interest in the imaging plane of the first ultrasound image.7. The method of claim 6, further comprising: electronically steeringthe transducer array.
 8. The method of claim 6, further comprising:physically deflecting the transducer array to steer the transducerarray.
 9. The method of claim 6, further comprising: rotating thetransducer array to steer the transducer array.
 10. The method of claim6, further comprising: articulating an articulating member affixed tothe transducer array to steer the transducer array.
 11. The method ofclaim 6, further comprising: manually moving the transducer array tosteer the transducer array.
 12. The method of claim 1, furthercomprising: steering the instrument guide with a motor.
 13. The methodof claim 1, further comprising: manually steering the instrument guide.14. The method of claim 1, further comprising: manually steering theinstrument guide with a robot.
 15. The method of claim 1, furthercomprising: manually steering the instrument guide free hand.
 16. Themethod of claim 1, further comprising: automatically steering theinstrument guide in response to receiving an input signal that activatesan auto-lock and guide mode.
 17. The method of claim 1, furthercomprising: displaying a message on a display monitor based on aposition correction signal.
 18. The method of claim 17, wherein themessage includes alphanumeric characters in human readable formatinstructing a user of the instrument guide to move the instrument guideby a fixed distance.
 19. The method of claim 1, wherein the registeringincludes mapping a location and a spatial orientation of the imagingplane of the first ultrasound image to a corresponding plane in the 3-Dimagethc message includes a graphics that indicates a direction ofmovement of the instrument guide.
 20. The method of claim 1, furthercomprising: determining the difference by computing a position errorthat includes a numerical value that indicates a magnitude and adirection of the difference; and steering the instrument guide based onthe position error.